The present invention relates to an apparatus for controlling the propulsion and direction of an air-cushion vehicle such as a hovercraft. More particularly, the present invention relates to an omnidirectional control apparatus for an air-cushion vehicle.
Air cushion vehicles include ground effect machines or hovercrafts which move by utilizing a cushion of air underneath a lower surface of a support body or frame. The cushion of air supports the body above the ground or a water surface. In general, air cushion vehicles have at least one lifting fan positioned in a support body or frame having a propeller or turbine with an axis of rotation positioned in a substantially vertical direction. The lifting fan blows air in a downward direction underneath the support body to create an air cushion. A skirt body extends down from the support body about its perimeter so that when the lifting fan blows air underneath the support body, the skirt body will trap air underneath the support body so that a cushion of air is created. This cushion of air allows the support body to freely float above the ground or water. The skirt body is generally a cylindrically shaped tube that extends the entire perimeter of the support body. The skirt body is generally not air tight but is porous to allow the lifting fan to inflate the skirt.
U.S. Pat. No. 4,964,835 to Suto also shows a hovercraft with at least one thrust fan that is located on the upper surface of the sport body. The thrust fan is used to move the air cushion vehicle in the horizontal plane. The thrust fan is typically mounted so that its propeller or turbine has an axis of rotation positioned substantially in a horizontal direction parallel to the upper surface of the support body and forces air in a generally rearward direction. Vanes having a fixed axis of rotation direct the flow of air to control the vehicle. However, the air can only be directed left or right thereby limiting directional control.
In order to control exiting air flow, some prior art thrust fans may be pivotally mounted to rotate right and left to steer and turn the air cushion vehicle. However, rotating the fan significantly increased the complexity and cost of the design. In other designs, a number of fins are positioned behind the thrust fan to further direct the thrust air in a desired direction to turn the air cushion vehicle. However this flow does not assist in lifting the vehicle.
A problem associated with prior art designs is that the turning of the air cushion vehicle using the prior art designs is not accurate or precise, thus the maneuverability of the vehicle is very poor.
Accordingly, it would be desirable to provide a control apparatus for an air cushion vehicle that is omnidirectional and can provide increased precision and accuracy in vehicle control.